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405 lines
10 KiB
405 lines
10 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* trace_seq.c |
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* |
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* Copyright (C) 2008-2014 Red Hat Inc, Steven Rostedt <[email protected]> |
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* |
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* The trace_seq is a handy tool that allows you to pass a descriptor around |
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* to a buffer that other functions can write to. It is similar to the |
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* seq_file functionality but has some differences. |
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* |
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* To use it, the trace_seq must be initialized with trace_seq_init(). |
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* This will set up the counters within the descriptor. You can call |
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* trace_seq_init() more than once to reset the trace_seq to start |
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* from scratch. |
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* |
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* The buffer size is currently PAGE_SIZE, although it may become dynamic |
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* in the future. |
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* |
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* A write to the buffer will either succeed or fail. That is, unlike |
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* sprintf() there will not be a partial write (well it may write into |
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* the buffer but it wont update the pointers). This allows users to |
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* try to write something into the trace_seq buffer and if it fails |
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* they can flush it and try again. |
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* |
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*/ |
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#include <linux/uaccess.h> |
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#include <linux/seq_file.h> |
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#include <linux/trace_seq.h> |
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/* How much buffer is left on the trace_seq? */ |
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#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq) |
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/* |
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* trace_seq should work with being initialized with 0s. |
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*/ |
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static inline void __trace_seq_init(struct trace_seq *s) |
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{ |
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if (unlikely(!s->seq.size)) |
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trace_seq_init(s); |
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} |
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/** |
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* trace_print_seq - move the contents of trace_seq into a seq_file |
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* @m: the seq_file descriptor that is the destination |
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* @s: the trace_seq descriptor that is the source. |
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* |
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* Returns 0 on success and non zero on error. If it succeeds to |
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* write to the seq_file it will reset the trace_seq, otherwise |
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* it does not modify the trace_seq to let the caller try again. |
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*/ |
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int trace_print_seq(struct seq_file *m, struct trace_seq *s) |
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{ |
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int ret; |
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__trace_seq_init(s); |
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ret = seq_buf_print_seq(m, &s->seq); |
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/* |
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* Only reset this buffer if we successfully wrote to the |
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* seq_file buffer. This lets the caller try again or |
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* do something else with the contents. |
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*/ |
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if (!ret) |
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trace_seq_init(s); |
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return ret; |
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} |
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/** |
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* trace_seq_printf - sequence printing of trace information |
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* @s: trace sequence descriptor |
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* @fmt: printf format string |
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* |
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* The tracer may use either sequence operations or its own |
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* copy to user routines. To simplify formatting of a trace |
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* trace_seq_printf() is used to store strings into a special |
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* buffer (@s). Then the output may be either used by |
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* the sequencer or pulled into another buffer. |
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*/ |
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void trace_seq_printf(struct trace_seq *s, const char *fmt, ...) |
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{ |
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unsigned int save_len = s->seq.len; |
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va_list ap; |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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va_start(ap, fmt); |
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seq_buf_vprintf(&s->seq, fmt, ap); |
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va_end(ap); |
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/* If we can't write it all, don't bother writing anything */ |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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} |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_printf); |
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/** |
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* trace_seq_bitmask - write a bitmask array in its ASCII representation |
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* @s: trace sequence descriptor |
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* @maskp: points to an array of unsigned longs that represent a bitmask |
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* @nmaskbits: The number of bits that are valid in @maskp |
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* |
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* Writes a ASCII representation of a bitmask string into @s. |
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*/ |
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void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp, |
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int nmaskbits) |
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{ |
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unsigned int save_len = s->seq.len; |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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seq_buf_printf(&s->seq, "%*pb", nmaskbits, maskp); |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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} |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_bitmask); |
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/** |
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* trace_seq_vprintf - sequence printing of trace information |
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* @s: trace sequence descriptor |
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* @fmt: printf format string |
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* |
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* The tracer may use either sequence operations or its own |
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* copy to user routines. To simplify formatting of a trace |
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* trace_seq_printf is used to store strings into a special |
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* buffer (@s). Then the output may be either used by |
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* the sequencer or pulled into another buffer. |
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*/ |
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void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args) |
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{ |
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unsigned int save_len = s->seq.len; |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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seq_buf_vprintf(&s->seq, fmt, args); |
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/* If we can't write it all, don't bother writing anything */ |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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} |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_vprintf); |
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/** |
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* trace_seq_bprintf - Write the printf string from binary arguments |
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* @s: trace sequence descriptor |
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* @fmt: The format string for the @binary arguments |
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* @binary: The binary arguments for @fmt. |
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* |
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* When recording in a fast path, a printf may be recorded with just |
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* saving the format and the arguments as they were passed to the |
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* function, instead of wasting cycles converting the arguments into |
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* ASCII characters. Instead, the arguments are saved in a 32 bit |
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* word array that is defined by the format string constraints. |
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* |
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* This function will take the format and the binary array and finish |
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* the conversion into the ASCII string within the buffer. |
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*/ |
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void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary) |
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{ |
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unsigned int save_len = s->seq.len; |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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seq_buf_bprintf(&s->seq, fmt, binary); |
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/* If we can't write it all, don't bother writing anything */ |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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return; |
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} |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_bprintf); |
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/** |
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* trace_seq_puts - trace sequence printing of simple string |
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* @s: trace sequence descriptor |
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* @str: simple string to record |
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* |
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* The tracer may use either the sequence operations or its own |
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* copy to user routines. This function records a simple string |
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* into a special buffer (@s) for later retrieval by a sequencer |
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* or other mechanism. |
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*/ |
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void trace_seq_puts(struct trace_seq *s, const char *str) |
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{ |
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unsigned int len = strlen(str); |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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if (len > TRACE_SEQ_BUF_LEFT(s)) { |
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s->full = 1; |
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return; |
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} |
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seq_buf_putmem(&s->seq, str, len); |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_puts); |
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/** |
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* trace_seq_putc - trace sequence printing of simple character |
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* @s: trace sequence descriptor |
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* @c: simple character to record |
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* |
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* The tracer may use either the sequence operations or its own |
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* copy to user routines. This function records a simple character |
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* into a special buffer (@s) for later retrieval by a sequencer |
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* or other mechanism. |
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*/ |
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void trace_seq_putc(struct trace_seq *s, unsigned char c) |
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{ |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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if (TRACE_SEQ_BUF_LEFT(s) < 1) { |
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s->full = 1; |
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return; |
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} |
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seq_buf_putc(&s->seq, c); |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_putc); |
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/** |
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* trace_seq_putmem - write raw data into the trace_seq buffer |
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* @s: trace sequence descriptor |
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* @mem: The raw memory to copy into the buffer |
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* @len: The length of the raw memory to copy (in bytes) |
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* |
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* There may be cases where raw memory needs to be written into the |
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* buffer and a strcpy() would not work. Using this function allows |
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* for such cases. |
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*/ |
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void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len) |
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{ |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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if (len > TRACE_SEQ_BUF_LEFT(s)) { |
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s->full = 1; |
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return; |
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} |
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seq_buf_putmem(&s->seq, mem, len); |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_putmem); |
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/** |
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* trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex |
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* @s: trace sequence descriptor |
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* @mem: The raw memory to write its hex ASCII representation of |
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* @len: The length of the raw memory to copy (in bytes) |
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* |
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* This is similar to trace_seq_putmem() except instead of just copying the |
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* raw memory into the buffer it writes its ASCII representation of it |
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* in hex characters. |
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*/ |
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void trace_seq_putmem_hex(struct trace_seq *s, const void *mem, |
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unsigned int len) |
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{ |
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unsigned int save_len = s->seq.len; |
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if (s->full) |
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return; |
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__trace_seq_init(s); |
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/* Each byte is represented by two chars */ |
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if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) { |
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s->full = 1; |
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return; |
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} |
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/* The added spaces can still cause an overflow */ |
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seq_buf_putmem_hex(&s->seq, mem, len); |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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return; |
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} |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_putmem_hex); |
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/** |
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* trace_seq_path - copy a path into the sequence buffer |
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* @s: trace sequence descriptor |
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* @path: path to write into the sequence buffer. |
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* |
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* Write a path name into the sequence buffer. |
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* |
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* Returns 1 if we successfully written all the contents to |
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* the buffer. |
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* Returns 0 if we the length to write is bigger than the |
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* reserved buffer space. In this case, nothing gets written. |
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*/ |
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int trace_seq_path(struct trace_seq *s, const struct path *path) |
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{ |
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unsigned int save_len = s->seq.len; |
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if (s->full) |
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return 0; |
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__trace_seq_init(s); |
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if (TRACE_SEQ_BUF_LEFT(s) < 1) { |
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s->full = 1; |
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return 0; |
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} |
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seq_buf_path(&s->seq, path, "\n"); |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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return 0; |
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} |
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return 1; |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_path); |
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/** |
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* trace_seq_to_user - copy the sequence buffer to user space |
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* @s: trace sequence descriptor |
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* @ubuf: The userspace memory location to copy to |
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* @cnt: The amount to copy |
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* |
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* Copies the sequence buffer into the userspace memory pointed to |
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* by @ubuf. It starts from the last read position (@s->readpos) |
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* and writes up to @cnt characters or till it reaches the end of |
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* the content in the buffer (@s->len), which ever comes first. |
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* |
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* On success, it returns a positive number of the number of bytes |
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* it copied. |
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* |
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* On failure it returns -EBUSY if all of the content in the |
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* sequence has been already read, which includes nothing in the |
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* sequence (@s->len == @s->readpos). |
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* |
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* Returns -EFAULT if the copy to userspace fails. |
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*/ |
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int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt) |
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{ |
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__trace_seq_init(s); |
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return seq_buf_to_user(&s->seq, ubuf, cnt); |
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} |
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EXPORT_SYMBOL_GPL(trace_seq_to_user); |
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int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str, |
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int prefix_type, int rowsize, int groupsize, |
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const void *buf, size_t len, bool ascii) |
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{ |
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unsigned int save_len = s->seq.len; |
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if (s->full) |
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return 0; |
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__trace_seq_init(s); |
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if (TRACE_SEQ_BUF_LEFT(s) < 1) { |
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s->full = 1; |
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return 0; |
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} |
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seq_buf_hex_dump(&(s->seq), prefix_str, |
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prefix_type, rowsize, groupsize, |
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buf, len, ascii); |
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if (unlikely(seq_buf_has_overflowed(&s->seq))) { |
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s->seq.len = save_len; |
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s->full = 1; |
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return 0; |
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} |
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return 1; |
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} |
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EXPORT_SYMBOL(trace_seq_hex_dump);
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